This paper is an overview of the current research activity in reverse osmosis (RO) membrane technology. Recent studies dwell on improving both membrane performance and membrane integrity in order to reduce RO operating costs. The main factors that affect membrane performance are high salt rejection and high permeation flux; and as such these two factors are carefully considered when discussing the effectiveness of each proposed modification, as well as in the assessment of each emerging membrane.

For thin film composite polyamide membranes, modifications target both the substrate and the thin barrier layer; including improvements in flux and rejection, fouling resistance and chlorine stability. Other polymers such as polyelectrolyte ultrathin separation membranes and highly thermal resistant poly(phthalazinone ether sulfone ketone) were also studied due to interesting properties that allow for use in desalination of industrial waters.

Inorganic membranes such as zeolite membranes were also mentioned to have potential for desalination due to their highly porous structures allowing for higher permeability compared to polymeric membranes. They also exhibit better chemical and physical resistance. In addition, materials such as clay and silica have also been studied due to their good chemical and thermal stabilities. Lastly, mixed matrix membranes consisting of polyamide matrix and inorganic fillers were also examined.

Significance:

Reverse osmosis is expected to continually serve as an effective approach in purifying water due to its simplicity and relatively low energy costs, compared to thermal based alternatives (flash and multi-effect distillation). This paper gives insight with regards to the current direction of membrane technology development; tackling modifications to existing membranes as well as the emergence of new materials which can be subjected to molecular dynamics simulations.